Principles of plastid reductive evolution illuminated by nonphotosynthetic chrysophytes

Richard G. Dorrell, Tomonori Azuma, Mami Nomura, Guillemette Audren de Kerdrel, Lucas Paoli, Shanshan Yang, Chris Bowler, Ken ichiro Ishii, Hideaki Miyashita, Gillian Gile, Ryoma Kamikawa

Research output: Contribution to journalArticlepeer-review

31 Scopus citations


The division of life into producers and consumers is blurred by evolution. For example, eukaryotic phototrophs can lose the capacity to photosynthesize, although they may retain vestigial plastids that perform other essential cellular functions. Chrysophyte algae have undergone a particularly large number of photosynthesis losses. Here, we present a plastid genome sequence from a nonphotosynthetic chrysophyte, “Spumella” sp. NIES-1846, and show that it has retained a nearly identical set of plastid-encoded functions as apicomplexan parasites. Our transcriptomic analysis of 12 different photosynthetic and nonphotosynthetic chrysophyte lineages reveals remarkable convergence in the functions of these nonphotosynthetic plastids, along with informative lineage-specific retentions and losses. At one extreme, Cornospumella fuschlensis retains many photosynthesis-associated proteins, although it appears to have lost the reductive pentose phosphate pathway and most plastid amino acid metabolism pathways. At the other extreme, Paraphysomonas lacks plastid-targeted proteins associated with gene expression and all metabolic pathways that require plastid-encoded partners, indicating a complete loss of plastid DNA in this genus. Intriguingly, some of the nucleus-encoded proteins that once functioned in the expression of the Paraphysomonas plastid genome have been retained. These proteins were likely to have been dual targeted to the plastid and mitochondria of the chrysophyte ancestor, and are uniquely targeted to the mitochondria in Paraphysomonas. Our comparative analyses provide insights into the process of functional reduction in nonphotosynthetic plastids.

Original languageEnglish (US)
Pages (from-to)6914-6923
Number of pages10
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number14
StatePublished - Apr 2 2019


  • Dual targeting
  • Heterotrophy
  • Ochrophyte
  • Phylogenomics
  • Protist

ASJC Scopus subject areas

  • General


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